The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-259842 filed Sep. 5, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a sheet processing apparatus for processing a sheet such as a copying machine or a printer, particularly to an improved sheet processing apparatus capable of coping with additional provision of a postprocessing apparatus, and an improved sheet transporting device used with the sheet processing apparatus.
2. Description of the Related Art
As a conventional sheet processing apparatus, for example, as shown in FIG. 6, there is known a sheet processing apparatus structured such that an image forming section (not shown) of an electrophotographic type is disposed inside an apparatus main body 200, a main body discharge section for discharging a sheet S on which an image is formed (for example, a structure including a pair of eject rollers in the vicinity of the exit of a eject passage) and a main body stack section (eject tray) 202 for placing and storing therein the sheet S discharged from the main body discharge section 201 are disposed in the upper portion of the apparatus main body 200.
The thus structured sheet processing apparatus, when compared with an apparatus of a type in which a eject tray is disposed on the lateral side of the apparatus main body 200, has an advantage that the installation space of the apparatus is reduced.
However, some users may wish to expand the system of the sheet processing apparatus, in which the eject tray 202 is disposed in the upper portion of the apparatus main body 200. For example, some users wish to add a postprocessing apparatus 210 incorporating therein a postprocessing unit such as a sorter, a stapler and a puncher.
Under such requests, if the postprocessing apparatus 210 is simply add to the lateral side of the apparatus main body 200, the sheet S with an image formed in the image forming section of the apparatus main body 200 side cannot be delivered into the postprocessing apparatus 210 side.
Therefore, conventionally, as shown in FIG. 6, there has been already proposed a technique in which the sheet S discharged from the main body discharge section 210 is transported to the postprocessing apparatus 210 side by a transport unit 220, while a stack portion 221 formed on the transport unit 220 is used to serve as a eject tray, whereby the sheet S can be ejected to the stack portion 221 (for example, see JP-A-10-69137 (pages 3 to 4, FIG. 1)).
Here, the transport unit 220 comprises a stack portion 221 on which the sheet S to be discharged from the main body discharge section 201 can be placed and stored, a stacking eject portion 222 (for example, a pair of eject rollers) for transporting the sheet S discharged from the main body discharge section 201 to the stack portion 221, a postprocessing transport portion 223 (for example, a plurality of transport rollers) disposed in the lower space of the stack portion 221 for transporting the sheet S discharged from the main body discharge section 201 to the postprocessing apparatus 210 side, and a switching gate 224 for switching the transport direction of the sheet S discharged from the main body discharge section 201 to the stacking eject portion 222 side or to the postprocessing transport portion 223 side.
However, in the transport unit 220 of the sheet processing apparatus of the above type, since the switching gate 224 and stacking eject portion 222 must be disposed downstream of the main body discharge section 201, it is indispensable to secure a space for provision of the switching gate 224 and stacking eject portion 222 within the transport unit 220. This raises a technical problem, that is, the dimension L of the sheet that can be placed in the stack portion 221 formed on the transport unit 220 is restricted (L less than L0, where L0 is the sheet dimension that can be placed on the main body stack section 202).
Also, in the transport unit 220, a transport passage (stack side transport passage) 225, which is branched to the stacking eject passage 222 side by the switching gate 224, branches with a given value of curvature with respect to a transport passage (a postprocessing side transport passage) 226 that goes to the postprocessing transport portion 223. In case where the large curvature of the stack side transport passage 225 is to be secured, as shown by a one-dot chained line in FIG. 7, the length dimension L of the stack portion 221 (the dimension of the sheet that can be placed) can be secured so as to be large to a certain degree. However, depending on the kinds of sheets, there arises a technical problem that a sheet such as a thick sheet cannot be transported.
In view of this, in case where the curvature of the stack side transport passage 225 is set so as to be small to a certain degree, as shown by a two-dot chained line, when the length dimension L of the stack portion 221 is to be secured so as to be large to a certain degree, the storage quantity h1 of sheets S decreases. And, as shown by a solid line in FIG. 7, when the storage quantity h2 of sheets S is secured so as to be large to a certain degree, there arises a technical problem that the length dimension L1 of the stack portion 221 is restricted extremely.
The present invention aims at solving the above-mentioned technical problems found in the conventional sheet processing apparatus. Accordingly, it is an object of the invention to provide a sheet processing apparatus which can cope with a system expansion condition such as additional provision of a postprocessing apparatus and can secure sufficient sheet placement performance (sheet transportability, and space) on the upper portion of the apparatus main body, and a sheet transporting device used in the sheet processing apparatus.
In attaining the above object, according to a first aspect of the invention, there is provided a sheet processing apparatus comprising: an apparatus main body; an image forming section disposed in the apparatus main body; a main body discharge section, from which a sheet with an image formed thereon is discharged, disposed in the upper portion of the apparatus main body; a main body stack section, in which the sheet discharged from the main body discharge section is placed and stored, disposed in the upper portion of the apparatus main body; a transport section disposed on the upper portion of the main body stack section for transporting the sheet discharged from the main body discharge section in a sheet eject direction on the upper portion of the main body stack section; an eject section disposed on the upper portion of the main body discharge section for ejecting the sheet with an image formed thereon through a second eject passage different from a eject passage of the main body discharge section; and a transport placement portion formed on the upper portion of the transport section for placing and storing therein the sheet ejected from the eject section.
According to a second aspect of the invention, there is provided a sheet processing apparatus comprising: an apparatus main body; an image forming section disposed in the apparatus main body; a main body discharge section, from which a sheet with an image formed thereon is discharged, disposed in the upper portion of the apparatus main body; a main body stack section, in which the sheet discharged from the main body discharge section is placed and stored, disposed in the upper portion of the apparatus main body; a transport section disposed on the upper portion of the main body stack section for transporting the sheet discharged from the main body discharge section in a sheet eject direction on the upper portion of the main body stack section; an eject section disposed on the upper portion of the main body discharge section for ejecting the sheet with an image formed thereon; and a transport placement portion formed on the upper portion of the transport section for placing and storing therein the sheet ejected from the eject section, wherein the allowable quantity of sheets to be placed in the transport placement portion is larger than that of the main body stack section.
According to a third aspect of the invention, there is provided a sheet transporting device to be mounted on a sheet processing apparatus having an apparatus main body; an image forming section disposed in the apparatus main body; a main body discharge section, from which a sheet with an image formed thereon is discharged, disposed in the upper portion of the apparatus main body; and a main body stack section, in which the sheet discharged from the main body discharge section is placed and stored, disposed in the upper portion of the apparatus main body, the sheet transporting device comprising: a transport section disposed on the upper portion of the main body stack section for transporting the sheet discharged from the main body discharge section in a sheet eject direction on the upper portion of the main body stack section; an eject section disposed on the upper portion of the main body discharge section for ejecting the sheet with an image formed thereon through a second eject passage different from a eject passage of the main body discharge section; and a transport placement portion formed on the upper portion of the transport section for placing and storing therein the sheet ejected from the eject section.